1. Field of the Invention
The present invention relates to a thermosetting resin composition, its cured product, and a process for producing this cured product, and particularly relates to a thermosetting resin composition applicable to various resin products for which an electrical insulating property, mold-ability and heat resistance are required, such as printed circuit boards, resin-sealed semiconductors, and resin-impregnated coils, its cured product, and a process for producing this cured product.
2. Description of the Prior Art
Polyaddition type polyimides such as bismaleimide are well-known examples of the resins of heat resistance class H. On the other hand, a homopolymer of aromatic dicyanamide is also known as a heat-resistant resin (See British Pat. No. 1322332). Although this polymer is more excellent in respect of heat resistance than the above polyimides, it is lacking in flexibility, so that it is extremely unsuitable for films, coating materials, prepreg materials and molding materials. Besides, a solvent is necessary to prepare a casting material from the aromatic dicyanamide because it is in the form of powder, and the use of a solvent gives rise to problems such as void formation and dimensional discrepancy, so that it is extremely unsuitable as a molding material.